Exige S Performance - cooked the brakes?

[GT3meupbaby]

Had a track day yesterday and about half way through the day the brakes started really grumbling and the pedal feel changed. Not sure they were any less effective but you could definitely hear them working.

Came in for a rest and they were really hot and the discs had gone a blueish tinge in places - have I killed them?

Find it strange if I have, as they are the AP callipers with Pagid RS14 pads (I think) that come as standard with the performance pack and up to this point had been awesome and the stopping power made more sense than it does on the road where I have found it at times excessive.

If so, what's the next step - can I bed them back in or is it new pads/dics?

Cheers,

GT3

[Esprit]

I think you'll find, a week or two of road use will see them return to normal... standard brakes should be up to all but endurance race use, especially with pads like RS14s

[cyberface]

The 4-pot AP Racing brakes and Pagid pads on the Performance Pack-equipped Exige S are massively over-specced for the car. There's NO way in hell you've 'cooked' them. Yes, with poor technique you can get them very hot, but as standard they are way more than the car needs.

One issue that *can* arise is that brake dust fills up the perforations in the brake disc, and this can compromise cooling. I've been advised on some track days to keep an eye on this, and if the 'holes' are full of black brake dust, just use a drill or similar to clear the dust out. The brakes will return to their previous performance.

Honestly, the big brakes on the PP are mental... someone on here a couple of weeks ago was complaining that they were almost 'over-braked' - certainly from cold it can be hard to *gently* slow the car down, but being able to stop from 145 mph in about 100 yards? I've never had a car that slows down as quick as my PP Exige, it's like a baseball bat to the face (my 18 yr old half-brother, who'd just passed his driving test, was up for the weekend... so I let him have a drive in the Exige and then took him out on a silly hoon. It pretty much re-adjusted his impression of what cars can do, heh)

[bogie]

Ive had problems with pad transfer with RS14s on the big AP 4 pots ...it could be that you are feeling ...try bedding them in again, but if it dosent go away, then likely its transfer, rather than warping

only thing you can do is skim the discs and change compound ...or new discs

Lotus finally admitted this is what happened to mine (this is years ago now, when the big 4 pot kit came out from them) and I got some new discs after 2 months mucking about complaining, and I then had RS42s from then on, and never had a problem ..they were a much better for road use, and no worse for track use (for me anyway)

[mrdemon]

standard wheels dont seem to offer any cooling effect

the 3 forged ones seem to.

who was the guy who sent his cup car back to Lotus not fit for purpose due to poor brakes and got his money back a few years ago.

any way I would not use standard wheels, fit ap disks and only use RS42, D2500 or CL pads

you can tell if they are over heating by feeling the wheels and seeing how hot they are.

Seen many people have issues with RS14 pads, may be they don't use they hard enough, they glaze over and then over heat !!!

Who knows but there clearly is an Issue with that set up on standard Exige wheels

Edited by mrdemon on Monday 22 February 17:13

[fergus]

bogie said:

Ive had problems with pad transfer with RS14s on the big AP 4 pots ...it could be that you are feeling ...try bedding them in again, but if it dosent go away, then likely its transfer, rather than warping

only thing you can do is skim the discs and change compound ...or new discs

Lotus finally admitted this is what happened to mine (this is years ago now, when the big 4 pot kit came out from them) and I got some new discs after 2 months mucking about complaining, and I then had RS42s from then on, and never had a problem ..they were a much better for road use, and no worse for track use (for me anyway)

If you've not followed the bedding process correctly, i.e. SLOWLY letting the resins get up to temp right through to the backing plate on the pad, the top surface of the pad can get too hot for its design characteristics and you may suffer some fade. You need to bed in discs too. Just because they are 'high performance' variants doesn't mean that they will perform optimally out of the box.

As an aside, the wheels will get hot, as the heat will get transfered through any surface that offers a heat soak, including the hubs.

Any pad transfer material can be removed by linshing the discs (best done off the car) with P80 grade wet and dry. Clean them off afterwards with brake cleaner and you should be good to go. Blueing of the discs does suggest the bedding process hasn't been followed at some point and you've introduced a massive thermal shock to the discs, as steel tends to blue at high temps.

RS42s aren't great if you're going to see very high temps, RS14 or RS15 are more thermally stable, but are more aggressive in their takeup and require a tad more finesse on the pedal to avoid lock up. I use Rs15 front and RS14 rear on my Caterham and have no problems. LFB on the first lap out to get some even heat into BOTH discs and pads, and you're good to go.

[GT3meupbaby]

I've got the forged alloys but the brakes are still definitely getting 'VERY' hot on the track.

Agree it still stops hard enough to make your eyeballs pop out, my nephew who passengered on track felt the same about it re-defining for him what a car can do..!

It was me that a few weeks back thought it was overbraked for the road and now I think what I've done is been too hard too quick on them on it's first track day on Saturday. Picked up the car with 3700 miles on it in January and to be honest think it was a bit of a garage queen in it's previous ownership and the brakes had never been worked hard enough to bed them in properly. I assued that now it has circa 5K on it the brakes would have been bedded in but maybe just never got them up to temp enough on the roads in Jan/Feb.

The discs are definitely blue in places especially on the front and it kind of looks like they are marked or some kind of thing is stuck to the disc in places - is this the 'pad transfer' mentioned? Would make sense that that is causing the grinding/rumbling as the disc is now not perfectly smooth.

I am very hard on the brakes on track, one of the instructors mentioned how late I was braking everywhere (no I'm not claiming to be the STIG..!) and I spoke to Hethel today who confirmed the RS14 is still a road legal pad and therefore if worked REALLY hard on track will always be a compromise.

Never had problems with RS-42s in old 111R although that was with standard callipers so think I will get the discs skimmed and put some RS-42s in unless anyone strongly disagrees that this will provide a solution?

Thanks all.

GT3

[bogie]

fergus said:

bogie said:

Ive had problems with pad transfer with RS14s on the big AP 4 pots ...it could be that you are feeling ...try bedding them in again, but if it dosent go away, then likely its transfer, rather than warping

only thing you can do is skim the discs and change compound ...or new discs

Lotus finally admitted this is what happened to mine (this is years ago now, when the big 4 pot kit came out from them) and I got some new discs after 2 months mucking about complaining, and I then had RS42s from then on, and never had a problem ..they were a much better for road use, and no worse for track use (for me anyway)

If you've not followed the bedding process correctly, i.e. SLOWLY letting the resins get up to temp right through to the backing plate on the pad, the top surface of the pad can get too hot for its design characteristics and you may suffer some fade. You need to bed in discs too. Just because they are 'high performance' variants doesn't mean that they will perform optimally out of the box.

As an aside, the wheels will get hot, as the heat will get transfered through any surface that offers a heat soak, including the hubs.

Any pad transfer material can be removed by linshing the discs (best done off the car) with P80 grade wet and dry. Clean them off afterwards with brake cleaner and you should be good to go. Blueing of the discs does suggest the bedding process hasn't been followed at some point and you've introduced a massive thermal shock to the discs, as steel tends to blue at high temps.

RS42s aren't great if you're going to see very high temps, RS14 or RS15 are more thermally stable, but are more aggressive in their takeup and require a tad more finesse on the pedal to avoid lock up. I use Rs15 front and RS14 rear on my Caterham and have no problems. LFB on the first lap out to get some even heat into BOTH discs and pads, and you're good to go.

thanks for the info Fergus....I did bed the pads according to Pagid instructions etc as Id previously run the same pads on different discs for quite some years without issue. It was the combination of a new large AP disc and RS14s that caused me issues.

It wasnt just me at the time either - apparently a few other people had done the same thing, with the OE big brake kit back then. I didnt know you could linish the discs though ..although to be fair, after paying nearly £2K for a new brake set-up and them being no use to me within a week, I was a little miffed to be taking them off and buggering about with them myself ! Lotus did revise the bedding in instructions after that, to be on the safe side

Ive not had a problem since, which is the main thing

[fergus]

GT3meupbaby said:

I assued that now it has circa 5K on it the brakes would have been bedded in but maybe just never got them up to temp enough on the roads in Jan/Feb.

It's not miles that bed them in, but thermal cycles! The ambient temp will not affect the temp of the disc to any large degree, as it will be operating around 350-450 degrees C! Despite having done another 1k miles, they *may* not have reached their optimum temp yet on the road. RS14s are a very aggressive pad with a very flat mu profile and offer a lot of torque!

Does the elise have facilities to fit cooling ducts (where air is distributed to the inner bell, rather than the disc face, or even the caliper as I have seen done before )?

[Exige77]

I was out at Odiham on Sunday with 4 pots and RS14 and my disc holes all filled up and I did start to get a little vibration mid way through the day. I have had this trouble before with RS14's and am thinking of moving to the Carbon Lorraine pads which are highly recomended by those that have them.

Anyone on here use CL pads ?

Ex77

[Ian_km]

You may find you don't have RS14's, if you have the solid discs that were fitted from part of the way through 2008 then they are actually Ferodo DS2500s.

I found this out after much messing about and ended up getting new pads direct from Lotus. They are similar to RS14s so still need the bedding in procedure.

[braddo]

If the discs are blue in patches maybe the OP's problems are due to insufficient cooling down of the brakes after a track session? That is, perhaps if the car gets parked when the brakes are still roasting hot the disc will go blue where the pad is.

Different car and brakes of course, but I'm pretty sure I had this during one track day and more careful cooling down on subsequent days meant I didn't get any more grumbles.

[NeilC]

I always got pad transfer with RS14's and 42's. Performance friction 01's FTW! Although noisy as hell on the road.